#include<bits/stdc++.h>
using namespace std;
using ll=long long;
constexpr ll mod=1e9+7;

int main()
{
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  ll a,b,c,d;
  cin>>a>>b>>c>>d;
  if (a==c || b==d || abs(a-c) + abs(b-d) <= 3) {
    cout << 1;
    return 0;
  } 
  cout << 2;

}